sys/kern/sys_pipe.c

   1 /*
   2  * Copyright (c) 1996 John S. Dyson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice immediately at the beginning of the file, without modification,
  10  *    this list of conditions, and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Absolutely no warranty of function or purpose is made by the author
  15  *    John S. Dyson.
  16  * 4. Modifications may be freely made to this file if the above conditions
  17  *    are met.
  18  *
  19  * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $
  20  * $DragonFly: src/sys/kern/sys_pipe.c,v 1.23 2004/05/21 14:26:28 hmp Exp $
  21  */
  22
  23 /*
  24  * This file contains a high-performance replacement for the socket-based
  25  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
  26  * all features of sockets, but does do everything that pipes normally
  27  * do.
  28  */
  29
  30 /*
  31  * This code has two modes of operation, a small write mode and a large
  32  * write mode.  The small write mode acts like conventional pipes with
  33  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
  34  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
  35  * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
  36  * the receiving process can copy it directly from the pages in the sending
  37  * process.
  38  *
  39  * If the sending process receives a signal, it is possible that it will
  40  * go away, and certainly its address space can change, because control
  41  * is returned back to the user-mode side.  In that case, the pipe code
  42  * arranges to copy the buffer supplied by the user process, to a pageable
  43  * kernel buffer, and the receiving process will grab the data from the
  44  * pageable kernel buffer.  Since signals don't happen all that often,
  45  * the copy operation is normally eliminated.
  46  *
  47  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
  48  * happen for small transfers so that the system will not spend all of
  49  * its time context switching.  PIPE_SIZE is constrained by the
  50  * amount of kernel virtual memory.
  51  */
  52
  53 #include <sys/param.h>
  54 #include <sys/systm.h>
  55 #include <sys/kernel.h>
  56 #include <sys/proc.h>
  57 #include <sys/fcntl.h>
  58 #include <sys/file.h>
  59 #include <sys/filedesc.h>
  60 #include <sys/filio.h>
  61 #include <sys/ttycom.h>
  62 #include <sys/stat.h>
  63 #include <sys/poll.h>
  64 #include <sys/select.h>
  65 #include <sys/signalvar.h>
  66 #include <sys/sysproto.h>
  67 #include <sys/pipe.h>
  68 #include <sys/vnode.h>
  69 #include <sys/uio.h>
  70 #include <sys/event.h>
  71 #include <sys/globaldata.h>
  72 #include <sys/module.h>
  73 #include <sys/malloc.h>
  74 #include <sys/sysctl.h>
  75
  76 #include <vm/vm.h>
  77 #include <vm/vm_param.h>
  78 #include <sys/lock.h>
  79 #include <vm/vm_object.h>
  80 #include <vm/vm_kern.h>
  81 #include <vm/vm_extern.h>
  82 #include <vm/pmap.h>
  83 #include <vm/vm_map.h>
  84 #include <vm/vm_page.h>
  85 #include <vm/vm_zone.h>
  86
  87 #include <sys/file2.h>
  88
  89 #include <machine/cpufunc.h>
  90
  91 /*
  92  * interfaces to the outside world
  93  */
  94 static int pipe_read (struct file *fp, struct uio *uio,
  95                 struct ucred *cred, int flags, struct thread *td);
  96 static int pipe_write (struct file *fp, struct uio *uio,
  97                 struct ucred *cred, int flags, struct thread *td);
  98 static int pipe_close (struct file *fp, struct thread *td);
  99 static int pipe_poll (struct file *fp, int events, struct ucred *cred,
 100                 struct thread *td);
 101 static int pipe_kqfilter (struct file *fp, struct knote *kn);
 102 static int pipe_stat (struct file *fp, struct stat *sb, struct thread *td);
 103 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct thread *td);
 104
 105 static struct fileops pipeops = {
 106         NULL,   /* port */
 107         NULL,   /* clone */
 108         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
 109         pipe_stat, pipe_close
 110 };
 111
 112 static void     filt_pipedetach(struct knote *kn);
 113 static int      filt_piperead(struct knote *kn, long hint);
 114 static int      filt_pipewrite(struct knote *kn, long hint);
 115
 116 static struct filterops pipe_rfiltops =
 117         { 1, NULL, filt_pipedetach, filt_piperead };
 118 static struct filterops pipe_wfiltops =
 119         { 1, NULL, filt_pipedetach, filt_pipewrite };
 120
 121 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
 122
 123 /*
 124  * Default pipe buffer size(s), this can be kind-of large now because pipe
 125  * space is pageable.  The pipe code will try to maintain locality of
 126  * reference for performance reasons, so small amounts of outstanding I/O
 127  * will not wipe the cache.
 128  */
 129 #define MINPIPESIZE (PIPE_SIZE/3)
 130 #define MAXPIPESIZE (2*PIPE_SIZE/3)
 131
 132 /*
 133  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
 134  * is there so that on large systems, we don't exhaust it.
 135  */
 136 #define MAXPIPEKVA (8*1024*1024)
 137
 138 /*
 139  * Limit for direct transfers, we cannot, of course limit
 140  * the amount of kva for pipes in general though.
 141  */
 142 #define LIMITPIPEKVA (16*1024*1024)
 143
 144 /*
 145  * Limit the number of "big" pipes
 146  */
 147 #define LIMITBIGPIPES   32
 148 #define PIPEQ_MAX_CACHE 16      /* per-cpu pipe structure cache */
 149
 150 static int pipe_maxbig = LIMITBIGPIPES;
 151 static int pipe_maxcache = PIPEQ_MAX_CACHE;
 152 static int pipe_nbig;
 153 static int pipe_bcache_alloc;
 154 static int pipe_bkmem_alloc;
 155 static int pipe_dwrite_enable = 1;      /* 0:copy, 1:kmem/sfbuf 2:force */
 156 static int pipe_dwrite_sfbuf = 1;       /* 0:kmem_map 1:sfbufs 2:sfbufs_dmap */
 157                                         /* 3:sfbuf_dmap w/ forced invlpg */
 158
 159 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
 160 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
 161         CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
 162 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
 163         CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
 164 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
 165         CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
 166 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_enable,
 167         CTLFLAG_RW, &pipe_dwrite_enable, 0, "1:enable/2:force direct writes");
 168 SYSCTL_INT(_kern_pipe, OID_AUTO, dwrite_sfbuf,
 169         CTLFLAG_RW, &pipe_dwrite_sfbuf, 0,
 170         "(if dwrite_enable) 0:kmem 1:sfbuf 2:sfbuf_dmap 3:sfbuf_dmap_forceinvlpg");
 171 #if !defined(NO_PIPE_SYSCTL_STATS)
 172 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
 173         CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
 174 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
 175         CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
 176 #endif
 177
 178 static void pipeclose (struct pipe *cpipe);
 179 static void pipe_free_kmem (struct pipe *cpipe);
 180 static int pipe_create (struct pipe **cpipep);
 181 static __inline int pipelock (struct pipe *cpipe, int catch);
 182 static __inline void pipeunlock (struct pipe *cpipe);
 183 static __inline void pipeselwakeup (struct pipe *cpipe);
 184 #ifndef PIPE_NODIRECT
 185 static int pipe_build_write_buffer (struct pipe *wpipe, struct uio *uio);
 186 static int pipe_direct_write (struct pipe *wpipe, struct uio *uio);
 187 static void pipe_clone_write_buffer (struct pipe *wpipe);
 188 #endif
 189 static int pipespace (struct pipe *cpipe, int size);
 190
 191 /*
 192  * The pipe system call for the DTYPE_PIPE type of pipes
 193  *
 194  * pipe_ARgs(int dummy)
 195  */
 196
 197 /* ARGSUSED */
 198 int
 199 pipe(struct pipe_args *uap)
 200 {
 201         struct thread *td = curthread;
 202         struct proc *p = td->td_proc;
 203         struct filedesc *fdp;
 204         struct file *rf, *wf;
 205         struct pipe *rpipe, *wpipe;
 206         int fd1, fd2, error;
 207
 208         KKASSERT(p);
 209         fdp = p->p_fd;
 210
 211         rpipe = wpipe = NULL;
 212         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
 213                 pipeclose(rpipe);
 214                 pipeclose(wpipe);
 215                 return (ENFILE);
 216         }
 217
 218         rpipe->pipe_state |= PIPE_DIRECTOK;
 219         wpipe->pipe_state |= PIPE_DIRECTOK;
 220
 221         /*
 222          * Select the direct-map features to use for this pipe.  Since the
 223          * sysctl's can change on the fly we record the settings when the
 224          * pipe is created.
 225          *
 226          * Generally speaking the system will default to what we consider
 227          * to be the best-balanced and most stable option.  Right now this
 228          * is SFBUF1.  Modes 2 and 3 are considered experiemental at the
 229          * moment.
 230          */
 231         wpipe->pipe_feature = PIPE_COPY;
 232         if (pipe_dwrite_enable) {
 233                 switch(pipe_dwrite_sfbuf) {
 234                 case 0:
 235                         wpipe->pipe_feature = PIPE_KMEM;
 236                         break;
 237                 case 1:
 238                         wpipe->pipe_feature = PIPE_SFBUF1;
 239                         break;
 240                 case 2:
 241                 case 3:
 242                         wpipe->pipe_feature = PIPE_SFBUF2;
 243                         break;
 244                 }
 245         }
 246         rpipe->pipe_feature = wpipe->pipe_feature;
 247
 248         error = falloc(p, &rf, &fd1);
 249         if (error) {
 250                 pipeclose(rpipe);
 251                 pipeclose(wpipe);
 252                 return (error);
 253         }
 254         fhold(rf);
 255         uap->sysmsg_fds[0] = fd1;
 256
 257         /*
 258          * Warning: once we've gotten past allocation of the fd for the
 259          * read-side, we can only drop the read side via fdrop() in order
 260          * to avoid races against processes which manage to dup() the read
 261          * side while we are blocked trying to allocate the write side.
 262          */
 263         rf->f_flag = FREAD | FWRITE;
 264         rf->f_type = DTYPE_PIPE;
 265         rf->f_data = (caddr_t)rpipe;
 266         rf->f_ops = &pipeops;
 267         error = falloc(p, &wf, &fd2);
 268         if (error) {
 269                 if (fdp->fd_ofiles[fd1] == rf) {
 270                         fdp->fd_ofiles[fd1] = NULL;
 271                         fdrop(rf, td);
 272                 }
 273                 fdrop(rf, td);
 274                 /* rpipe has been closed by fdrop(). */
 275                 pipeclose(wpipe);
 276                 return (error);
 277         }
 278         wf->f_flag = FREAD | FWRITE;
 279         wf->f_type = DTYPE_PIPE;
 280         wf->f_data = (caddr_t)wpipe;
 281         wf->f_ops = &pipeops;
 282         uap->sysmsg_fds[1] = fd2;
 283
 284         rpipe->pipe_peer = wpipe;
 285         wpipe->pipe_peer = rpipe;
 286         fdrop(rf, td);
 287
 288         return (0);
 289 }
 290
 291 /*
 292  * Allocate kva for pipe circular buffer, the space is pageable
 293  * This routine will 'realloc' the size of a pipe safely, if it fails
 294  * it will retain the old buffer.
 295  * If it fails it will return ENOMEM.
 296  */
 297 static int
 298 pipespace(struct pipe *cpipe, int size)
 299 {
 300         struct vm_object *object;
 301         caddr_t buffer;
 302         int npages, error;
 303
 304         npages = round_page(size) / PAGE_SIZE;
 305         object = cpipe->pipe_buffer.object;
 306
 307         /*
 308          * [re]create the object if necessary and reserve space for it
 309          * in the kernel_map.  The object and memory are pageable.  On
 310          * success, free the old resources before assigning the new
 311          * ones.
 312          */
 313         if (object == NULL || object->size != npages) {
 314                 object = vm_object_allocate(OBJT_DEFAULT, npages);
 315                 buffer = (caddr_t) vm_map_min(kernel_map);
 316
 317                 error = vm_map_find(kernel_map, object, 0,
 318                         (vm_offset_t *) &buffer, size, 1,
 319                         VM_PROT_ALL, VM_PROT_ALL, 0);
 320
 321                 if (error != KERN_SUCCESS) {
 322                         vm_object_deallocate(object);
 323                         return (ENOMEM);
 324                 }
 325                 pipe_free_kmem(cpipe);
 326                 cpipe->pipe_buffer.object = object;
 327                 cpipe->pipe_buffer.buffer = buffer;
 328                 cpipe->pipe_buffer.size = size;
 329                 ++pipe_bkmem_alloc;
 330         } else {
 331                 ++pipe_bcache_alloc;
 332         }
 333         cpipe->pipe_buffer.in = 0;
 334         cpipe->pipe_buffer.out = 0;
 335         cpipe->pipe_buffer.cnt = 0;
 336         return (0);
 337 }
 338
 339 /*
 340  * Initialize and allocate VM and memory for pipe, pulling the pipe from
 341  * our per-cpu cache if possible.  For now make sure it is sized for the
 342  * smaller PIPE_SIZE default.
 343  */
 344 static int
 345 pipe_create(cpipep)
 346         struct pipe **cpipep;
 347 {
 348         globaldata_t gd = mycpu;
 349         struct pipe *cpipe;
 350         int error;
 351
 352         if ((cpipe = gd->gd_pipeq) != NULL) {
 353                 gd->gd_pipeq = cpipe->pipe_peer;
 354                 --gd->gd_pipeqcount;
 355                 cpipe->pipe_peer = NULL;
 356         } else {
 357                 cpipe = malloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
 358         }
 359         *cpipep = cpipe;
 360         if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
 361                 return (error);
 362         vfs_timestamp(&cpipe->pipe_ctime);
 363         cpipe->pipe_atime = cpipe->pipe_ctime;
 364         cpipe->pipe_mtime = cpipe->pipe_ctime;
 365         return (0);
 366 }
 367
 368
 369 /*
 370  * lock a pipe for I/O, blocking other access
 371  */
 372 static __inline int
 373 pipelock(cpipe, catch)
 374         struct pipe *cpipe;
 375         int catch;
 376 {
 377         int error;
 378
 379         while (cpipe->pipe_state & PIPE_LOCK) {
 380                 cpipe->pipe_state |= PIPE_LWANT;
 381                 error = tsleep(cpipe, (catch ? PCATCH : 0), "pipelk", 0);
 382                 if (error != 0)
 383                         return (error);
 384         }
 385         cpipe->pipe_state |= PIPE_LOCK;
 386         return (0);
 387 }
 388
 389 /*
 390  * unlock a pipe I/O lock
 391  */
 392 static __inline void
 393 pipeunlock(cpipe)
 394         struct pipe *cpipe;
 395 {
 396
 397         cpipe->pipe_state &= ~PIPE_LOCK;
 398         if (cpipe->pipe_state & PIPE_LWANT) {
 399                 cpipe->pipe_state &= ~PIPE_LWANT;
 400                 wakeup(cpipe);
 401         }
 402 }
 403
 404 static __inline void
 405 pipeselwakeup(cpipe)
 406         struct pipe *cpipe;
 407 {
 408
 409         if (cpipe->pipe_state & PIPE_SEL) {
 410                 cpipe->pipe_state &= ~PIPE_SEL;
 411                 selwakeup(&cpipe->pipe_sel);
 412         }
 413         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
 414                 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
 415         KNOTE(&cpipe->pipe_sel.si_note, 0);
 416 }
 417
 418 /* ARGSUSED */
 419 static int
 420 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred,
 421         int flags, struct thread *td)
 422 {
 423         struct pipe *rpipe = (struct pipe *) fp->f_data;
 424         int error;
 425         int nread = 0;
 426         u_int size;
 427
 428         ++rpipe->pipe_busy;
 429         error = pipelock(rpipe, 1);
 430         if (error)
 431                 goto unlocked_error;
 432
 433         while (uio->uio_resid) {
 434                 caddr_t va;
 435
 436                 if (rpipe->pipe_buffer.cnt > 0) {
 437                         /*
 438                          * normal pipe buffer receive
 439                          */
 440                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
 441                         if (size > rpipe->pipe_buffer.cnt)
 442                                 size = rpipe->pipe_buffer.cnt;
 443                         if (size > (u_int) uio->uio_resid)
 444                                 size = (u_int) uio->uio_resid;
 445
 446                         error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
 447                                         size, uio);
 448                         if (error)
 449                                 break;
 450
 451                         rpipe->pipe_buffer.out += size;
 452                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
 453                                 rpipe->pipe_buffer.out = 0;
 454
 455                         rpipe->pipe_buffer.cnt -= size;
 456
 457                         /*
 458                          * If there is no more to read in the pipe, reset
 459                          * its pointers to the beginning.  This improves
 460                          * cache hit stats.
 461                          */
 462                         if (rpipe->pipe_buffer.cnt == 0) {
 463                                 rpipe->pipe_buffer.in = 0;
 464                                 rpipe->pipe_buffer.out = 0;
 465                         }
 466                         nread += size;
 467 #ifndef PIPE_NODIRECT
 468                 } else if (rpipe->pipe_kva &&
 469                            rpipe->pipe_feature == PIPE_KMEM &&
 470                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 471                                == PIPE_DIRECTW
 472                 ) {
 473                         /*
 474                          * Direct copy using source-side kva mapping
 475                          */
 476                         size = rpipe->pipe_map.xio_bytes;
 477                         if (size > (u_int)uio->uio_resid)
 478                                 size = (u_int)uio->uio_resid;
 479                         va = (caddr_t)rpipe->pipe_kva + rpipe->pipe_map.xio_offset;
 480                         error = uiomove(va, size, uio);
 481                         if (error)
 482                                 break;
 483                         nread += size;
 484                         rpipe->pipe_map.xio_offset += size;
 485                         rpipe->pipe_map.xio_bytes -= size;
 486                         if (rpipe->pipe_map.xio_bytes == 0) {
 487                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 488                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 489                                 wakeup(rpipe);
 490                         }
 491                 } else if (rpipe->pipe_map.xio_bytes &&
 492                            rpipe->pipe_kva &&
 493                            rpipe->pipe_feature == PIPE_SFBUF2 &&
 494                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 495                                == PIPE_DIRECTW
 496                 ) {
 497                         /*
 498                          * Direct copy, bypassing a kernel buffer.  We cannot
 499                          * mess with the direct-write buffer until
 500                          * PIPE_DIRECTIP is cleared.  In order to prevent
 501                          * the pipe_write code from racing itself in
 502                          * direct_write, we set DIRECTIP when we clear
 503                          * DIRECTW after we have exhausted the buffer.
 504                          */
 505                         if (pipe_dwrite_sfbuf == 3)
 506                                 rpipe->pipe_kvamask = 0;
 507                         pmap_qenter2(rpipe->pipe_kva, rpipe->pipe_map.xio_pages,
 508                                     rpipe->pipe_map.xio_npages,
 509                                     &rpipe->pipe_kvamask);
 510                         size = rpipe->pipe_map.xio_bytes;
 511                         if (size > (u_int)uio->uio_resid)
 512                                 size = (u_int)uio->uio_resid;
 513                         va = (caddr_t)rpipe->pipe_kva +
 514                                 rpipe->pipe_map.xio_offset;
 515                         error = uiomove(va, size, uio);
 516                         if (error)
 517                                 break;
 518                         nread += size;
 519                         rpipe->pipe_map.xio_offset += size;
 520                         rpipe->pipe_map.xio_bytes -= size;
 521                         if (rpipe->pipe_map.xio_bytes == 0) {
 522                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 523                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 524                                 wakeup(rpipe);
 525                         }
 526                 } else if (rpipe->pipe_map.xio_bytes &&
 527                            rpipe->pipe_feature == PIPE_SFBUF1 &&
 528                            (rpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP))
 529                                 == PIPE_DIRECTW
 530                 ) {
 531                         /*
 532                          * Direct copy, bypassing a kernel buffer.  We cannot
 533                          * mess with the direct-write buffer until
 534                          * PIPE_DIRECTIP is cleared.  In order to prevent
 535                          * the pipe_write code from racing itself in
 536                          * direct_write, we set DIRECTIP when we clear
 537                          * DIRECTW after we have exhausted the buffer.
 538                          */
 539                         error = xio_uio_copy(&rpipe->pipe_map, uio, &size);
 540                         if (error)
 541                                 break;
 542                         nread += size;
 543                         if (rpipe->pipe_map.xio_bytes == 0) {
 544                                 rpipe->pipe_state |= PIPE_DIRECTIP;
 545                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
 546                                 wakeup(rpipe);
 547                         }
 548 #endif
 549                 } else {
 550                         /*
 551                          * detect EOF condition
 552                          * read returns 0 on EOF, no need to set error
 553                          */
 554                         if (rpipe->pipe_state & PIPE_EOF)
 555                                 break;
 556
 557                         /*
 558                          * If the "write-side" has been blocked, wake it up now.
 559                          */
 560                         if (rpipe->pipe_state & PIPE_WANTW) {
 561                                 rpipe->pipe_state &= ~PIPE_WANTW;
 562                                 wakeup(rpipe);
 563                         }
 564
 565                         /*
 566                          * Break if some data was read.
 567                          */
 568                         if (nread > 0)
 569                                 break;
 570
 571                         /*
 572                          * Unlock the pipe buffer for our remaining
 573                          * processing.  We will either break out with an
 574                          * error or we will sleep and relock to loop.
 575                          */
 576                         pipeunlock(rpipe);
 577
 578                         /*
 579                          * Handle non-blocking mode operation or
 580                          * wait for more data.
 581                          */
 582                         if (fp->f_flag & FNONBLOCK) {
 583                                 error = EAGAIN;
 584                         } else {
 585                                 rpipe->pipe_state |= PIPE_WANTR;
 586                                 if ((error = tsleep(rpipe, PCATCH|PNORESCHED,
 587                                     "piperd", 0)) == 0) {
 588                                         error = pipelock(rpipe, 1);
 589                                 }
 590                         }
 591                         if (error)
 592                                 goto unlocked_error;
 593                 }
 594         }
 595         pipeunlock(rpipe);
 596
 597         if (error == 0)
 598                 vfs_timestamp(&rpipe->pipe_atime);
 599 unlocked_error:
 600         --rpipe->pipe_busy;
 601
 602         /*
 603          * PIPE_WANT processing only makes sense if pipe_busy is 0.
 604          */
 605         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
 606                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
 607                 wakeup(rpipe);
 608         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
 609                 /*
 610                  * Handle write blocking hysteresis.
 611                  */
 612                 if (rpipe->pipe_state & PIPE_WANTW) {
 613                         rpipe->pipe_state &= ~PIPE_WANTW;
 614                         wakeup(rpipe);
 615                 }
 616         }
 617
 618         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
 619                 pipeselwakeup(rpipe);
 620         return (error);
 621 }
 622
 623 #ifndef PIPE_NODIRECT
 624 /*
 625  * Map the sending processes' buffer into kernel space and wire it.
 626  * This is similar to a physical write operation.
 627  */
 628 static int
 629 pipe_build_write_buffer(wpipe, uio)
 630         struct pipe *wpipe;
 631         struct uio *uio;
 632 {
 633         int error;
 634         u_int size;
 635
 636         size = (u_int) uio->uio_iov->iov_len;
 637         if (size > wpipe->pipe_buffer.size)
 638                 size = wpipe->pipe_buffer.size;
 639
 640         error = xio_init_ubuf(&wpipe->pipe_map, uio->uio_iov->iov_base,
 641                                 size, XIOF_READ);
 642         if (error)
 643                 return(error);
 644
 645         /*
 646          * Create a kernel map for KMEM and SFBUF2 copy modes.  SFBUF2 will
 647          * map the pages on the target while KMEM maps the pages now.
 648          */
 649         switch(wpipe->pipe_feature) {
 650         case PIPE_KMEM:
 651         case PIPE_SFBUF2:
 652                 if (wpipe->pipe_kva == NULL) {
 653                         wpipe->pipe_kva =
 654                             kmem_alloc_nofault(kernel_map, XIO_INTERNAL_SIZE);
 655                         wpipe->pipe_kvamask = 0;
 656                 }
 657                 if (wpipe->pipe_feature == PIPE_KMEM) {
 658                         pmap_qenter(wpipe->pipe_kva, wpipe->pipe_map.xio_pages,
 659                                     wpipe->pipe_map.xio_npages);
 660                 }
 661                 break;
 662         default:
 663                 break;
 664         }
 665
 666         /*
 667          * And update the uio data.  The XIO might have loaded fewer bytes
 668          * then requested so reload 'size'.
 669          */
 670         size = wpipe->pipe_map.xio_bytes;
 671         uio->uio_iov->iov_len -= size;
 672         uio->uio_iov->iov_base += size;
 673         if (uio->uio_iov->iov_len == 0)
 674                 uio->uio_iov++;
 675         uio->uio_resid -= size;
 676         uio->uio_offset += size;
 677         return (0);
 678 }
 679
 680 /*
 681  * In the case of a signal, the writing process might go away.  This
 682  * code copies the data into the circular buffer so that the source
 683  * pages can be freed without loss of data.
 684  */
 685 static void
 686 pipe_clone_write_buffer(wpipe)
 687         struct pipe *wpipe;
 688 {
 689         int size;
 690
 691         size = wpipe->pipe_map.xio_bytes;
 692
 693         KKASSERT(size <= wpipe->pipe_buffer.size);
 694
 695         wpipe->pipe_buffer.in = size;
 696         wpipe->pipe_buffer.out = 0;
 697         wpipe->pipe_buffer.cnt = size;
 698         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 699
 700         xio_copy_xtok(&wpipe->pipe_map, wpipe->pipe_buffer.buffer, size);
 701         xio_release(&wpipe->pipe_map);
 702         if (wpipe->pipe_kva) {
 703                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 704                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 705                 wpipe->pipe_kva = NULL;
 706         }
 707 }
 708
 709 /*
 710  * This implements the pipe buffer write mechanism.  Note that only
 711  * a direct write OR a normal pipe write can be pending at any given time.
 712  * If there are any characters in the pipe buffer, the direct write will
 713  * be deferred until the receiving process grabs all of the bytes from
 714  * the pipe buffer.  Then the direct mapping write is set-up.
 715  */
 716 static int
 717 pipe_direct_write(wpipe, uio)
 718         struct pipe *wpipe;
 719         struct uio *uio;
 720 {
 721         int error;
 722
 723 retry:
 724         while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 725                 if (wpipe->pipe_state & PIPE_WANTR) {
 726                         wpipe->pipe_state &= ~PIPE_WANTR;
 727                         wakeup(wpipe);
 728                 }
 729                 wpipe->pipe_state |= PIPE_WANTW;
 730                 error = tsleep(wpipe, PCATCH, "pipdww", 0);
 731                 if (error)
 732                         goto error2;
 733                 if (wpipe->pipe_state & PIPE_EOF) {
 734                         error = EPIPE;
 735                         goto error2;
 736                 }
 737         }
 738         KKASSERT(wpipe->pipe_map.xio_bytes == 0);
 739         if (wpipe->pipe_buffer.cnt > 0) {
 740                 if (wpipe->pipe_state & PIPE_WANTR) {
 741                         wpipe->pipe_state &= ~PIPE_WANTR;
 742                         wakeup(wpipe);
 743                 }
 744
 745                 wpipe->pipe_state |= PIPE_WANTW;
 746                 error = tsleep(wpipe, PCATCH, "pipdwc", 0);
 747                 if (error)
 748                         goto error2;
 749                 if (wpipe->pipe_state & PIPE_EOF) {
 750                         error = EPIPE;
 751                         goto error2;
 752                 }
 753                 goto retry;
 754         }
 755
 756         /*
 757          * Build our direct-write buffer
 758          */
 759         wpipe->pipe_state |= PIPE_DIRECTW | PIPE_DIRECTIP;
 760         error = pipe_build_write_buffer(wpipe, uio);
 761         if (error)
 762                 goto error1;
 763         wpipe->pipe_state &= ~PIPE_DIRECTIP;
 764
 765         /*
 766          * Wait until the receiver has snarfed the data.  Since we are likely
 767          * going to sleep we optimize the case and yield synchronously,
 768          * possibly avoiding the tsleep().
 769          */
 770         error = 0;
 771         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
 772                 if (wpipe->pipe_state & PIPE_EOF) {
 773                         pipelock(wpipe, 0);
 774                         xio_release(&wpipe->pipe_map);
 775                         if (wpipe->pipe_kva) {
 776                                 pmap_qremove(wpipe->pipe_kva, XIO_INTERNAL_PAGES);
 777                                 kmem_free(kernel_map, wpipe->pipe_kva, XIO_INTERNAL_SIZE);
 778                                 wpipe->pipe_kva = NULL;
 779                         }
 780                         pipeunlock(wpipe);
 781                         pipeselwakeup(wpipe);
 782                         error = EPIPE;
 783                         goto error1;
 784                 }
 785                 if (wpipe->pipe_state & PIPE_WANTR) {
 786                         wpipe->pipe_state &= ~PIPE_WANTR;
 787                         wakeup(wpipe);
 788                 }
 789                 pipeselwakeup(wpipe);
 790                 error = tsleep(wpipe, PCATCH|PNORESCHED, "pipdwt", 0);
 791         }
 792         pipelock(wpipe,0);
 793         if (wpipe->pipe_state & PIPE_DIRECTW) {
 794                 /*
 795                  * this bit of trickery substitutes a kernel buffer for
 796                  * the process that might be going away.
 797                  */
 798                 pipe_clone_write_buffer(wpipe);
 799                 KKASSERT((wpipe->pipe_state & PIPE_DIRECTIP) == 0);
 800         } else {
 801                 /*
 802                  * note: The pipe_kva mapping is not qremove'd here.  For
 803                  * legacy PIPE_KMEM mode this constitutes an improvement
 804                  * over the original FreeBSD-4 algorithm.  For PIPE_SFBUF2
 805                  * mode the kva mapping must not be removed to get the
 806                  * caching benefit.
 807                  *
 808                  * For testing purposes we will give the original algorithm
 809                  * the benefit of the doubt 'what it could have been', and
 810                  * keep the optimization.
 811                  */
 812                 KKASSERT(wpipe->pipe_state & PIPE_DIRECTIP);
 813                 xio_release(&wpipe->pipe_map);
 814                 wpipe->pipe_state &= ~PIPE_DIRECTIP;
 815         }
 816         pipeunlock(wpipe);
 817         return (error);
 818
 819         /*
 820          * Direct-write error, clear the direct write flags.
 821          */
 822 error1:
 823         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTIP);
 824         /* fallthrough */
 825
 826         /*
 827          * General error, wakeup the other side if it happens to be sleeping.
 828          */
 829 error2:
 830         wakeup(wpipe);
 831         return (error);
 832 }
 833 #endif
 834
 835 static int
 836 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred,
 837         int flags, struct thread *td)
 838 {
 839         int error = 0;
 840         int orig_resid;
 841         struct pipe *wpipe, *rpipe;
 842
 843         rpipe = (struct pipe *) fp->f_data;
 844         wpipe = rpipe->pipe_peer;
 845
 846         /*
 847          * detect loss of pipe read side, issue SIGPIPE if lost.
 848          */
 849         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 850                 return (EPIPE);
 851         }
 852         ++wpipe->pipe_busy;
 853
 854         /*
 855          * If it is advantageous to resize the pipe buffer, do
 856          * so.
 857          */
 858         if ((uio->uio_resid > PIPE_SIZE) &&
 859                 (pipe_nbig < pipe_maxbig) &&
 860                 (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) == 0 &&
 861                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
 862                 (wpipe->pipe_buffer.cnt == 0)) {
 863
 864                 if ((error = pipelock(wpipe,1)) == 0) {
 865                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
 866                                 pipe_nbig++;
 867                         pipeunlock(wpipe);
 868                 }
 869         }
 870
 871         /*
 872          * If an early error occured unbusy and return, waking up any pending
 873          * readers.
 874          */
 875         if (error) {
 876                 --wpipe->pipe_busy;
 877                 if ((wpipe->pipe_busy == 0) &&
 878                     (wpipe->pipe_state & PIPE_WANT)) {
 879                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 880                         wakeup(wpipe);
 881                 }
 882                 return(error);
 883         }
 884
 885         KASSERT(wpipe->pipe_buffer.buffer != NULL, ("pipe buffer gone"));
 886
 887         orig_resid = uio->uio_resid;
 888
 889         while (uio->uio_resid) {
 890                 int space;
 891
 892 #ifndef PIPE_NODIRECT
 893                 /*
 894                  * If the transfer is large, we can gain performance if
 895                  * we do process-to-process copies directly.
 896                  * If the write is non-blocking, we don't use the
 897                  * direct write mechanism.
 898                  *
 899                  * The direct write mechanism will detect the reader going
 900                  * away on us.
 901                  */
 902                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT ||
 903                     pipe_dwrite_enable > 1) &&
 904                     (fp->f_flag & FNONBLOCK) == 0 &&
 905                     pipe_dwrite_enable) {
 906                         error = pipe_direct_write( wpipe, uio);
 907                         if (error)
 908                                 break;
 909                         continue;
 910                 }
 911 #endif
 912
 913                 /*
 914                  * Pipe buffered writes cannot be coincidental with
 915                  * direct writes.  We wait until the currently executing
 916                  * direct write is completed before we start filling the
 917                  * pipe buffer.  We break out if a signal occurs or the
 918                  * reader goes away.
 919                  */
 920         retrywrite:
 921                 while (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 922                         if (wpipe->pipe_state & PIPE_WANTR) {
 923                                 wpipe->pipe_state &= ~PIPE_WANTR;
 924                                 wakeup(wpipe);
 925                         }
 926                         error = tsleep(wpipe, PCATCH, "pipbww", 0);
 927                         if (wpipe->pipe_state & PIPE_EOF)
 928                                 break;
 929                         if (error)
 930                                 break;
 931                 }
 932                 if (wpipe->pipe_state & PIPE_EOF) {
 933                         error = EPIPE;
 934                         break;
 935                 }
 936
 937                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 938
 939                 /* Writes of size <= PIPE_BUF must be atomic. */
 940                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
 941                         space = 0;
 942
 943                 /*
 944                  * Write to fill, read size handles write hysteresis.  Also
 945                  * additional restrictions can cause select-based non-blocking
 946                  * writes to spin.
 947                  */
 948                 if (space > 0) {
 949                         if ((error = pipelock(wpipe,1)) == 0) {
 950                                 int size;       /* Transfer size */
 951                                 int segsize;    /* first segment to transfer */
 952
 953                                 /*
 954                                  * It is possible for a direct write to
 955                                  * slip in on us... handle it here...
 956                                  */
 957                                 if (wpipe->pipe_state & (PIPE_DIRECTW|PIPE_DIRECTIP)) {
 958                                         pipeunlock(wpipe);
 959                                         goto retrywrite;
 960                                 }
 961                                 /*
 962                                  * If a process blocked in uiomove, our
 963                                  * value for space might be bad.
 964                                  *
 965                                  * XXX will we be ok if the reader has gone
 966                                  * away here?
 967                                  */
 968                                 if (space > wpipe->pipe_buffer.size -
 969                                     wpipe->pipe_buffer.cnt) {
 970                                         pipeunlock(wpipe);
 971                                         goto retrywrite;
 972                                 }
 973
 974                                 /*
 975                                  * Transfer size is minimum of uio transfer
 976                                  * and free space in pipe buffer.
 977                                  */
 978                                 if (space > uio->uio_resid)
 979                                         size = uio->uio_resid;
 980                                 else
 981                                         size = space;
 982                                 /*
 983                                  * First segment to transfer is minimum of
 984                                  * transfer size and contiguous space in
 985                                  * pipe buffer.  If first segment to transfer
 986                                  * is less than the transfer size, we've got
 987                                  * a wraparound in the buffer.
 988                                  */
 989                                 segsize = wpipe->pipe_buffer.size -
 990                                         wpipe->pipe_buffer.in;
 991                                 if (segsize > size)
 992                                         segsize = size;
 993
 994                                 /* Transfer first segment */
 995
 996                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
 997                                                 segsize, uio);
 998
 999                                 if (error == 0 && segsize < size) {
1000                                         /*
1001                                          * Transfer remaining part now, to
1002                                          * support atomic writes.  Wraparound
1003                                          * happened.
1004                                          */
1005                                         if (wpipe->pipe_buffer.in + segsize !=
1006                                             wpipe->pipe_buffer.size)
1007                                                 panic("Expected pipe buffer wraparound disappeared");
1008
1009                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
1010                                                         size - segsize, uio);
1011                                 }
1012                                 if (error == 0) {
1013                                         wpipe->pipe_buffer.in += size;
1014                                         if (wpipe->pipe_buffer.in >=
1015                                             wpipe->pipe_buffer.size) {
1016                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
1017                                                         panic("Expected wraparound bad");
1018                                                 wpipe->pipe_buffer.in = size - segsize;
1019                                         }
1020
1021                                         wpipe->pipe_buffer.cnt += size;
1022                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
1023                                                 panic("Pipe buffer overflow");
1024
1025                                 }
1026                                 pipeunlock(wpipe);
1027                         }
1028                         if (error)
1029                                 break;
1030
1031                 } else {
1032                         /*
1033                          * If the "read-side" has been blocked, wake it up now
1034                          * and yield to let it drain synchronously rather
1035                          * then block.
1036                          */
1037                         if (wpipe->pipe_state & PIPE_WANTR) {
1038                                 wpipe->pipe_state &= ~PIPE_WANTR;
1039                                 wakeup(wpipe);
1040                         }
1041
1042                         /*
1043                          * don't block on non-blocking I/O
1044                          */
1045                         if (fp->f_flag & FNONBLOCK) {
1046                                 error = EAGAIN;
1047                                 break;
1048                         }
1049
1050                         /*
1051                          * We have no more space and have something to offer,
1052                          * wake up select/poll.
1053                          */
1054                         pipeselwakeup(wpipe);
1055
1056                         wpipe->pipe_state |= PIPE_WANTW;
1057                         error = tsleep(wpipe, PCATCH|PNORESCHED, "pipewr", 0);
1058                         if (error != 0)
1059                                 break;
1060                         /*
1061                          * If read side wants to go away, we just issue a signal
1062                          * to ourselves.
1063                          */
1064                         if (wpipe->pipe_state & PIPE_EOF) {
1065                                 error = EPIPE;
1066                                 break;
1067                         }
1068                 }
1069         }
1070
1071         --wpipe->pipe_busy;
1072
1073         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
1074                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
1075                 wakeup(wpipe);
1076         } else if (wpipe->pipe_buffer.cnt > 0) {
1077                 /*
1078                  * If we have put any characters in the buffer, we wake up
1079                  * the reader.
1080                  */
1081                 if (wpipe->pipe_state & PIPE_WANTR) {
1082                         wpipe->pipe_state &= ~PIPE_WANTR;
1083                         wakeup(wpipe);
1084                 }
1085         }
1086
1087         /*
1088          * Don't return EPIPE if I/O was successful
1089          */
1090         if ((wpipe->pipe_buffer.cnt == 0) &&
1091             (uio->uio_resid == 0) &&
1092             (error == EPIPE)) {
1093                 error = 0;
1094         }
1095
1096         if (error == 0)
1097                 vfs_timestamp(&wpipe->pipe_mtime);
1098
1099         /*
1100          * We have something to offer,
1101          * wake up select/poll.
1102          */
1103         if (wpipe->pipe_buffer.cnt)
1104                 pipeselwakeup(wpipe);
1105
1106         return (error);
1107 }
1108
1109 /*
1110  * we implement a very minimal set of ioctls for compatibility with sockets.
1111  */
1112 int
1113 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct thread *td)
1114 {
1115         struct pipe *mpipe = (struct pipe *)fp->f_data;
1116
1117         switch (cmd) {
1118
1119         case FIONBIO:
1120                 return (0);
1121
1122         case FIOASYNC:
1123                 if (*(int *)data) {
1124                         mpipe->pipe_state |= PIPE_ASYNC;
1125                 } else {
1126                         mpipe->pipe_state &= ~PIPE_ASYNC;
1127                 }
1128                 return (0);
1129
1130         case FIONREAD:
1131                 if (mpipe->pipe_state & PIPE_DIRECTW) {
1132                         *(int *)data = mpipe->pipe_map.xio_bytes;
1133                 } else {
1134                         *(int *)data = mpipe->pipe_buffer.cnt;
1135                 }
1136                 return (0);
1137
1138         case FIOSETOWN:
1139                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
1140
1141         case FIOGETOWN:
1142                 *(int *)data = fgetown(mpipe->pipe_sigio);
1143                 return (0);
1144
1145         /* This is deprecated, FIOSETOWN should be used instead. */
1146         case TIOCSPGRP:
1147                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
1148
1149         /* This is deprecated, FIOGETOWN should be used instead. */
1150         case TIOCGPGRP:
1151                 *(int *)data = -fgetown(mpipe->pipe_sigio);
1152                 return (0);
1153
1154         }
1155         return (ENOTTY);
1156 }
1157
1158 int
1159 pipe_poll(struct file *fp, int events, struct ucred *cred, struct thread *td)
1160 {
1161         struct pipe *rpipe = (struct pipe *)fp->f_data;
1162         struct pipe *wpipe;
1163         int revents = 0;
1164
1165         wpipe = rpipe->pipe_peer;
1166         if (events & (POLLIN | POLLRDNORM))
1167                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
1168                     (rpipe->pipe_buffer.cnt > 0) ||
1169                     (rpipe->pipe_state & PIPE_EOF))
1170                         revents |= events & (POLLIN | POLLRDNORM);
1171
1172         if (events & (POLLOUT | POLLWRNORM))
1173                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
1174                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
1175                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
1176                         revents |= events & (POLLOUT | POLLWRNORM);
1177
1178         if ((rpipe->pipe_state & PIPE_EOF) ||
1179             (wpipe == NULL) ||
1180             (wpipe->pipe_state & PIPE_EOF))
1181                 revents |= POLLHUP;
1182
1183         if (revents == 0) {
1184                 if (events & (POLLIN | POLLRDNORM)) {
1185                         selrecord(td, &rpipe->pipe_sel);
1186                         rpipe->pipe_state |= PIPE_SEL;
1187                 }
1188
1189                 if (events & (POLLOUT | POLLWRNORM)) {
1190                         selrecord(td, &wpipe->pipe_sel);
1191                         wpipe->pipe_state |= PIPE_SEL;
1192                 }
1193         }
1194
1195         return (revents);
1196 }
1197
1198 static int
1199 pipe_stat(struct file *fp, struct stat *ub, struct thread *td)
1200 {
1201         struct pipe *pipe = (struct pipe *)fp->f_data;
1202
1203         bzero((caddr_t)ub, sizeof(*ub));
1204         ub->st_mode = S_IFIFO;
1205         ub->st_blksize = pipe->pipe_buffer.size;
1206         ub->st_size = pipe->pipe_buffer.cnt;
1207         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1208         ub->st_atimespec = pipe->pipe_atime;
1209         ub->st_mtimespec = pipe->pipe_mtime;
1210         ub->st_ctimespec = pipe->pipe_ctime;
1211         /*
1212          * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1213          * st_flags, st_gen.
1214          * XXX (st_dev, st_ino) should be unique.
1215          */
1216         return (0);
1217 }
1218
1219 /* ARGSUSED */
1220 static int
1221 pipe_close(struct file *fp, struct thread *td)
1222 {
1223         struct pipe *cpipe = (struct pipe *)fp->f_data;
1224
1225         fp->f_ops = &badfileops;
1226         fp->f_data = NULL;
1227         funsetown(cpipe->pipe_sigio);
1228         pipeclose(cpipe);
1229         return (0);
1230 }
1231
1232 static void
1233 pipe_free_kmem(struct pipe *cpipe)
1234 {
1235         if (cpipe->pipe_buffer.buffer != NULL) {
1236                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1237                         --pipe_nbig;
1238                 kmem_free(kernel_map,
1239                         (vm_offset_t)cpipe->pipe_buffer.buffer,
1240                         cpipe->pipe_buffer.size);
1241                 cpipe->pipe_buffer.buffer = NULL;
1242                 cpipe->pipe_buffer.object = NULL;
1243         }
1244 #ifndef PIPE_NODIRECT
1245         KKASSERT(cpipe->pipe_map.xio_bytes == 0 &&
1246                 cpipe->pipe_map.xio_offset == 0 &&
1247                 cpipe->pipe_map.xio_npages == 0);
1248 #endif
1249 }
1250
1251 /*
1252  * shutdown the pipe
1253  */
1254 static void
1255 pipeclose(struct pipe *cpipe)
1256 {
1257         globaldata_t gd;
1258         struct pipe *ppipe;
1259
1260         if (cpipe == NULL)
1261                 return;
1262
1263         pipeselwakeup(cpipe);
1264
1265         /*
1266          * If the other side is blocked, wake it up saying that
1267          * we want to close it down.
1268          */
1269         while (cpipe->pipe_busy) {
1270                 wakeup(cpipe);
1271                 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
1272                 tsleep(cpipe, 0, "pipecl", 0);
1273         }
1274
1275         /*
1276          * Disconnect from peer
1277          */
1278         if ((ppipe = cpipe->pipe_peer) != NULL) {
1279                 pipeselwakeup(ppipe);
1280
1281                 ppipe->pipe_state |= PIPE_EOF;
1282                 wakeup(ppipe);
1283                 KNOTE(&ppipe->pipe_sel.si_note, 0);
1284                 ppipe->pipe_peer = NULL;
1285         }
1286
1287         if (cpipe->pipe_kva) {
1288                 pmap_qremove(cpipe->pipe_kva, XIO_INTERNAL_PAGES);
1289                 kmem_free(kernel_map, cpipe->pipe_kva, XIO_INTERNAL_SIZE);
1290                 cpipe->pipe_kva = NULL;
1291         }
1292
1293         /*
1294          * free or cache resources
1295          */
1296         gd = mycpu;
1297         if (gd->gd_pipeqcount >= pipe_maxcache ||
1298             cpipe->pipe_buffer.size != PIPE_SIZE
1299         ) {
1300                 pipe_free_kmem(cpipe);
1301                 free(cpipe, M_PIPE);
1302         } else {
1303                 KKASSERT(cpipe->pipe_map.xio_npages == 0 &&
1304                         cpipe->pipe_map.xio_bytes == 0 &&
1305                         cpipe->pipe_map.xio_offset == 0);
1306                 cpipe->pipe_state = 0;
1307                 cpipe->pipe_busy = 0;
1308                 cpipe->pipe_peer = gd->gd_pipeq;
1309                 gd->gd_pipeq = cpipe;
1310                 ++gd->gd_pipeqcount;
1311         }
1312 }
1313
1314 /*ARGSUSED*/
1315 static int
1316 pipe_kqfilter(struct file *fp, struct knote *kn)
1317 {
1318         struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
1319
1320         switch (kn->kn_filter) {
1321         case EVFILT_READ:
1322                 kn->kn_fop = &pipe_rfiltops;
1323                 break;
1324         case EVFILT_WRITE:
1325                 kn->kn_fop = &pipe_wfiltops;
1326                 cpipe = cpipe->pipe_peer;
1327                 if (cpipe == NULL)
1328                         /* other end of pipe has been closed */
1329                         return (EPIPE);
1330                 break;
1331         default:
1332                 return (1);
1333         }
1334         kn->kn_hook = (caddr_t)cpipe;
1335
1336         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1337         return (0);
1338 }
1339
1340 static void
1341 filt_pipedetach(struct knote *kn)
1342 {
1343         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1344
1345         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1346 }
1347
1348 /*ARGSUSED*/
1349 static int
1350 filt_piperead(struct knote *kn, long hint)
1351 {
1352         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1353         struct pipe *wpipe = rpipe->pipe_peer;
1354
1355         kn->kn_data = rpipe->pipe_buffer.cnt;
1356         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
1357                 kn->kn_data = rpipe->pipe_map.xio_bytes;
1358
1359         if ((rpipe->pipe_state & PIPE_EOF) ||
1360             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1361                 kn->kn_flags |= EV_EOF;
1362                 return (1);
1363         }
1364         return (kn->kn_data > 0);
1365 }
1366
1367 /*ARGSUSED*/
1368 static int
1369 filt_pipewrite(struct knote *kn, long hint)
1370 {
1371         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1372         struct pipe *wpipe = rpipe->pipe_peer;
1373
1374         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
1375                 kn->kn_data = 0;
1376                 kn->kn_flags |= EV_EOF;
1377                 return (1);
1378         }
1379         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
1380         if (wpipe->pipe_state & PIPE_DIRECTW)
1381                 kn->kn_data = 0;
1382
1383         return (kn->kn_data >= PIPE_BUF);
1384 }